change # of comments shown in edit-comments.php?

I run a blog with a fairly active comment section, and find it convenient to be able to read all of the comments from many different posts on a single page, edit-comments.php .

What I’d like to do is modify the number of comments shown on edit-comments.php , so that the most recent 100 comments are shown, rather than the default number. Can someone please tell me how to do this? I know it can’t be too hard – I did it once in the past, but now can’t figure out what I did.

Thanks!